diff --git a/src/prebuilt/wasm2c_source_declarations.cc b/src/prebuilt/wasm2c_source_declarations.cc
index 9841120bb..db7ad6854 100644
--- a/src/prebuilt/wasm2c_source_declarations.cc
+++ b/src/prebuilt/wasm2c_source_declarations.cc
@@ -165,24 +165,24 @@ R"w2c_template(  (CHECK_CALL_INDIRECT(table, ft, x),       \
 R"w2c_template(   DO_CALL_INDIRECT(table, t, x, __VA_ARGS__))
 )w2c_template"
 R"w2c_template(
-#if __has_builtin(__builtin_add_overflow)
+static inline bool add_overflow(uint64_t a, uint64_t b, uint64_t* resptr) {
 )w2c_template"
-R"w2c_template(#define add_overflow(a, b, resptr) __builtin_add_overflow(a, b, resptr)
+R"w2c_template(#if __has_builtin(__builtin_add_overflow)
 )w2c_template"
-R"w2c_template(#elif defined(_MSC_VER)
+R"w2c_template(  return __builtin_add_overflow(a, b, resptr);
 )w2c_template"
-R"w2c_template(static inline bool add_overflow(uint64_t a, uint64_t b, uint64_t* resptr) {
+R"w2c_template(#elif defined(_MSC_VER)
 )w2c_template"
 R"w2c_template(  return _addcarry_u64(0, a, b, resptr);
 )w2c_template"
-R"w2c_template(}
-)w2c_template"
 R"w2c_template(#else
 )w2c_template"
 R"w2c_template(#error "Missing implementation of __builtin_add_overflow or _addcarry_u64"
 )w2c_template"
 R"w2c_template(#endif
 )w2c_template"
+R"w2c_template(}
+)w2c_template"
 R"w2c_template(
 #define RANGE_CHECK(mem, offset, len)              \
 )w2c_template"
diff --git a/src/template/wasm2c.declarations.c b/src/template/wasm2c.declarations.c
index 913787fd1..9a827c2f4 100644
--- a/src/template/wasm2c.declarations.c
+++ b/src/template/wasm2c.declarations.c
@@ -89,15 +89,15 @@ static inline bool func_types_eq(const wasm_rt_func_type_t a,
   (CHECK_CALL_INDIRECT(table, ft, x),       \
    DO_CALL_INDIRECT(table, t, x, __VA_ARGS__))
 
+static inline bool add_overflow(uint64_t a, uint64_t b, uint64_t* resptr) {
 #if __has_builtin(__builtin_add_overflow)
-#define add_overflow(a, b, resptr) __builtin_add_overflow(a, b, resptr)
+  return __builtin_add_overflow(a, b, resptr);
 #elif defined(_MSC_VER)
-static inline bool add_overflow(uint64_t a, uint64_t b, uint64_t* resptr) {
   return _addcarry_u64(0, a, b, resptr);
-}
 #else
 #error "Missing implementation of __builtin_add_overflow or _addcarry_u64"
 #endif
+}
 
 #define RANGE_CHECK(mem, offset, len)              \
   do {                                             \
diff --git a/test/wasm2c/add.txt b/test/wasm2c/add.txt
index 5906e65d5..9db5e3901 100644
--- a/test/wasm2c/add.txt
+++ b/test/wasm2c/add.txt
@@ -156,15 +156,15 @@ static inline bool func_types_eq(const wasm_rt_func_type_t a,
   (CHECK_CALL_INDIRECT(table, ft, x),       \
    DO_CALL_INDIRECT(table, t, x, __VA_ARGS__))
 
+static inline bool add_overflow(uint64_t a, uint64_t b, uint64_t* resptr) {
 #if __has_builtin(__builtin_add_overflow)
-#define add_overflow(a, b, resptr) __builtin_add_overflow(a, b, resptr)
+  return __builtin_add_overflow(a, b, resptr);
 #elif defined(_MSC_VER)
-static inline bool add_overflow(uint64_t a, uint64_t b, uint64_t* resptr) {
   return _addcarry_u64(0, a, b, resptr);
-}
 #else
 #error "Missing implementation of __builtin_add_overflow or _addcarry_u64"
 #endif
+}
 
 #define RANGE_CHECK(mem, offset, len)              \
   do {                                             \
diff --git a/test/wasm2c/check-imports.txt b/test/wasm2c/check-imports.txt
index 80ad6bc97..b69170daa 100644
--- a/test/wasm2c/check-imports.txt
+++ b/test/wasm2c/check-imports.txt
@@ -180,15 +180,15 @@ static inline bool func_types_eq(const wasm_rt_func_type_t a,
   (CHECK_CALL_INDIRECT(table, ft, x),       \
    DO_CALL_INDIRECT(table, t, x, __VA_ARGS__))
 
+static inline bool add_overflow(uint64_t a, uint64_t b, uint64_t* resptr) {
 #if __has_builtin(__builtin_add_overflow)
-#define add_overflow(a, b, resptr) __builtin_add_overflow(a, b, resptr)
+  return __builtin_add_overflow(a, b, resptr);
 #elif defined(_MSC_VER)
-static inline bool add_overflow(uint64_t a, uint64_t b, uint64_t* resptr) {
   return _addcarry_u64(0, a, b, resptr);
-}
 #else
 #error "Missing implementation of __builtin_add_overflow or _addcarry_u64"
 #endif
+}
 
 #define RANGE_CHECK(mem, offset, len)              \
   do {                                             \
diff --git a/test/wasm2c/export-names.txt b/test/wasm2c/export-names.txt
index 86c50c593..2eb5e379a 100644
--- a/test/wasm2c/export-names.txt
+++ b/test/wasm2c/export-names.txt
@@ -180,15 +180,15 @@ static inline bool func_types_eq(const wasm_rt_func_type_t a,
   (CHECK_CALL_INDIRECT(table, ft, x),       \
    DO_CALL_INDIRECT(table, t, x, __VA_ARGS__))
 
+static inline bool add_overflow(uint64_t a, uint64_t b, uint64_t* resptr) {
 #if __has_builtin(__builtin_add_overflow)
-#define add_overflow(a, b, resptr) __builtin_add_overflow(a, b, resptr)
+  return __builtin_add_overflow(a, b, resptr);
 #elif defined(_MSC_VER)
-static inline bool add_overflow(uint64_t a, uint64_t b, uint64_t* resptr) {
   return _addcarry_u64(0, a, b, resptr);
-}
 #else
 #error "Missing implementation of __builtin_add_overflow or _addcarry_u64"
 #endif
+}
 
 #define RANGE_CHECK(mem, offset, len)              \
   do {                                             \
diff --git a/test/wasm2c/hello.txt b/test/wasm2c/hello.txt
index e9c72f756..c3d1866d7 100644
--- a/test/wasm2c/hello.txt
+++ b/test/wasm2c/hello.txt
@@ -188,15 +188,15 @@ static inline bool func_types_eq(const wasm_rt_func_type_t a,
   (CHECK_CALL_INDIRECT(table, ft, x),       \
    DO_CALL_INDIRECT(table, t, x, __VA_ARGS__))
 
+static inline bool add_overflow(uint64_t a, uint64_t b, uint64_t* resptr) {
 #if __has_builtin(__builtin_add_overflow)
-#define add_overflow(a, b, resptr) __builtin_add_overflow(a, b, resptr)
+  return __builtin_add_overflow(a, b, resptr);
 #elif defined(_MSC_VER)
-static inline bool add_overflow(uint64_t a, uint64_t b, uint64_t* resptr) {
   return _addcarry_u64(0, a, b, resptr);
-}
 #else
 #error "Missing implementation of __builtin_add_overflow or _addcarry_u64"
 #endif
+}
 
 #define RANGE_CHECK(mem, offset, len)              \
   do {                                             \
diff --git a/test/wasm2c/minimal.txt b/test/wasm2c/minimal.txt
index 1ac7290c7..a606cce25 100644
--- a/test/wasm2c/minimal.txt
+++ b/test/wasm2c/minimal.txt
@@ -150,15 +150,15 @@ static inline bool func_types_eq(const wasm_rt_func_type_t a,
   (CHECK_CALL_INDIRECT(table, ft, x),       \
    DO_CALL_INDIRECT(table, t, x, __VA_ARGS__))
 
+static inline bool add_overflow(uint64_t a, uint64_t b, uint64_t* resptr) {
 #if __has_builtin(__builtin_add_overflow)
-#define add_overflow(a, b, resptr) __builtin_add_overflow(a, b, resptr)
+  return __builtin_add_overflow(a, b, resptr);
 #elif defined(_MSC_VER)
-static inline bool add_overflow(uint64_t a, uint64_t b, uint64_t* resptr) {
   return _addcarry_u64(0, a, b, resptr);
-}
 #else
 #error "Missing implementation of __builtin_add_overflow or _addcarry_u64"
 #endif
+}
 
 #define RANGE_CHECK(mem, offset, len)              \
   do {                                             \
diff --git a/test/wasm2c/tail-calls.txt b/test/wasm2c/tail-calls.txt
index 3431496c6..6a6f442c0 100644
--- a/test/wasm2c/tail-calls.txt
+++ b/test/wasm2c/tail-calls.txt
@@ -180,15 +180,15 @@ static inline bool func_types_eq(const wasm_rt_func_type_t a,
   (CHECK_CALL_INDIRECT(table, ft, x),       \
    DO_CALL_INDIRECT(table, t, x, __VA_ARGS__))
 
+static inline bool add_overflow(uint64_t a, uint64_t b, uint64_t* resptr) {
 #if __has_builtin(__builtin_add_overflow)
-#define add_overflow(a, b, resptr) __builtin_add_overflow(a, b, resptr)
+  return __builtin_add_overflow(a, b, resptr);
 #elif defined(_MSC_VER)
-static inline bool add_overflow(uint64_t a, uint64_t b, uint64_t* resptr) {
   return _addcarry_u64(0, a, b, resptr);
-}
 #else
 #error "Missing implementation of __builtin_add_overflow or _addcarry_u64"
 #endif
+}
 
 #define RANGE_CHECK(mem, offset, len)              \
   do {                                             \
diff --git a/wasm2c/examples/fac/fac.c b/wasm2c/examples/fac/fac.c
index e216d4384..312bd8535 100644
--- a/wasm2c/examples/fac/fac.c
+++ b/wasm2c/examples/fac/fac.c
@@ -108,15 +108,15 @@ static inline bool func_types_eq(const wasm_rt_func_type_t a,
   (CHECK_CALL_INDIRECT(table, ft, x),       \
    DO_CALL_INDIRECT(table, t, x, __VA_ARGS__))
 
+static inline bool add_overflow(uint64_t a, uint64_t b, uint64_t* resptr) {
 #if __has_builtin(__builtin_add_overflow)
-#define add_overflow(a, b, resptr) __builtin_add_overflow(a, b, resptr)
+  return __builtin_add_overflow(a, b, resptr);
 #elif defined(_MSC_VER)
-static inline bool add_overflow(uint64_t a, uint64_t b, uint64_t* resptr) {
   return _addcarry_u64(0, a, b, resptr);
-}
 #else
 #error "Missing implementation of __builtin_add_overflow or _addcarry_u64"
 #endif
+}
 
 #define RANGE_CHECK(mem, offset, len)              \
   do {                                             \